1. Field
One embodiment of the invention relates to an infrared signal decode circuit and an infrared signal decode method.
2. Description of the Related Art
Normally, a remote controller (hereinafter, also referred to as a remote) is used to operate an electronic device such as a television (TV) receiver or the like. In general, the remote includes a communication module that employs infrared light.
Such remote is configured by an infrared light transmitter and an infrared light reception module. The infrared light transmitter is widely referred as a “remote,” and is built inside a portable housing. The infrared light transmitter modulates an electric signal associated with the operation through the operation button or the like with low frequency of 30 KHz to 60 KHz, and drives an infrared light emitting diode with the modulated signal. The infrared light transmitter is operated by a battery. The infrared light reception module is built inside an electronic device such as a TV receiver or the like.
The infrared light receiver amplifies, when necessary, an infrared light received by a photo-detector including a photo-diode, and demodulates the amplified infrared light to obtain an operation signal. With the operation signal, a remotely controlled device, i.e., an electronic device that is controlled through the remote controller, is controlled to be turned on/off. In general, the infrared light receiver includes a bandpass filter (BPF) provided for processing a signal that is to be input to the detection circuit. The BPF only passes a particular frequency band to reduce influence of the external noise (for example, see Japanese Patent Application Publication (KOKAI) No. 2005-347858).
However, the circuit size and current consumption of the infrared light receiver becomes large due to the inclusion of the BPF. Further, when an analog BPF is used in the infrared light receiver, the BPF properties during the manufacture of the BPF or while it is in use are required to be adjusted, which increases the cost.